This invention relates to an assembly for taking a liquid sample from one or more selected levels in a tank.
Previously arrangements for taking a liquid sample from a selected level in a tank have included a plurality of tubes extending to different depths in the tank from where it is desired to take a sample. Pressure in the tank or gravity may be used to obtain samples from the tubes. See for example, U.S. Pat. No. 2,090,514 (1937). If the tubes extend upwardly from the bottom of the tank, with drain valves in the bottom to remove the samples, the tubes fill up with liquid as the tank is filled. Thus a representative sample of the liquid at the particular level in the tank at the time the sample is taken is not obtained when the drain valves are opened. Furthermore, to completely unload the tank, the drain holes from all sampling tubes must be opened and the liquid collected.
Another sampling arrangement includes a tube extending vertically within the tank having an operator within the tube having a valve at its inner end which opens and closes the inner opening into the tube. Gravity or super-atmospheric pressure in the tank force a sample out when the valve is moved to the open position. See U.S. Pat. Nos. 1,638,333 and 2,404,087. However, if the valve and/or the operator becomes stuck the lading must be drained and the operator must enter the tank to repair and/or replace the damaged parts.